diff --git a/app/features/auth/core/user.server.ts b/app/features/auth/core/user.server.ts
index 03667dba5..6b8efe8c9 100644
--- a/app/features/auth/core/user.server.ts
+++ b/app/features/auth/core/user.server.ts
@@ -1,6 +1,10 @@
 import { IMPERSONATED_SESSION_KEY, SESSION_KEY } from "./authenticator.server";
 import { authSessionStorage } from "./session.server";
-import { type AuthenticatedUser, getUserContext } from "./user-context.server";
+import {
+	type AuthenticatedUser,
+	getUserContext,
+	userAsyncLocalStorage,
+} from "./user-context.server";
 
 export type { AuthenticatedUser };
 
@@ -32,6 +36,13 @@ export function actorIdOrNull(): number | null {
 	return getUser()?.id ?? null;
 }
 
+/** Id of the acting user, or null when there is no actor *or* no request
+ *  context at all (e.g. cron routines). Never throws, unlike actorIdOrNull —
+ *  use for ambient side effects that may also run outside of a request. */
+export function actorIdOrNullSafe(): number | null {
+	return userAsyncLocalStorage.getStore()?.user?.id ?? null;
+}
+
 export async function isImpersonating(request: Request) {
 	const session = await authSessionStorage.getSession(
 		request.headers.get("Cookie"),
diff --git a/app/features/chat/ChatSystemMessage.server.ts b/app/features/chat/ChatSystemMessage.server.ts
index b27933a7b..c8edae989 100644
--- a/app/features/chat/ChatSystemMessage.server.ts
+++ b/app/features/chat/ChatSystemMessage.server.ts
@@ -1,6 +1,7 @@
 import { add } from "date-fns";
 import { nanoid } from "nanoid";
 import { ServerConfig } from "~/config.server";
+import { actorIdOrNullSafe } from "~/features/auth/core/user.server";
 import * as UserRepository from "~/features/user-page/UserRepository.server";
 import { IS_E2E_TEST_RUN } from "~/utils/e2e";
 import invariant from "~/utils/invariant";
@@ -60,7 +61,7 @@ export const send: ChatSystemMessageService["send"] = (partialMsg) => {
 			context: partialMsg.context,
 			type: partialMsg.type,
 			revalidateOnly: partialMsg.revalidateOnly,
-			authorUserId: partialMsg.authorUserId,
+			authorUserId: partialMsg.authorUserId ?? actorIdOrNullSafe() ?? undefined,
 		};
 	});
 
diff --git a/app/features/scrims/actions/scrims.$id.server.ts b/app/features/scrims/actions/scrims.$id.server.ts
index b17fbd3eb..17fa58291 100644
--- a/app/features/scrims/actions/scrims.$id.server.ts
+++ b/app/features/scrims/actions/scrims.$id.server.ts
@@ -103,7 +103,7 @@ export const action = async ({ request, params }: ActionFunctionArgs) => {
 				serializedPool,
 			});
 
-			broadcastRevalidate({ post, user });
+			broadcastRevalidate(post);
 			break;
 		}
 		case "REMOVE_MAP_LIST": {
@@ -111,7 +111,7 @@ export const action = async ({ request, params }: ActionFunctionArgs) => {
 
 			await ScrimMapListRepository.deleteMapList(post.id, viewerSide);
 
-			broadcastRevalidate({ post, user });
+			broadcastRevalidate(post);
 			break;
 		}
 		case "REPORT_MAP": {
@@ -127,7 +127,7 @@ export const action = async ({ request, params }: ActionFunctionArgs) => {
 				winnerSide: data.winnerSide,
 			});
 
-			broadcastRevalidate({ post, user });
+			broadcastRevalidate(post);
 			break;
 		}
 		case "UNDO_MAP": {
@@ -138,7 +138,7 @@ export const action = async ({ request, params }: ActionFunctionArgs) => {
 
 			await ScrimMapRepository.undoMostRecentMap(post.id);
 
-			broadcastRevalidate({ post, user });
+			broadcastRevalidate(post);
 			break;
 		}
 		case "REPLAY_MAP": {
@@ -203,18 +203,13 @@ async function loadMapByMapContext({
 	return { viewerSide: viewerSide!, maps, mapLists };
 }
 
-function broadcastRevalidate({
-	post,
-	user,
-}: {
-	post: NonNullable<Awaited<ReturnType<typeof ScrimPostRepository.findById>>>;
-	user: ReturnType<typeof requireUser>;
-}) {
+function broadcastRevalidate(
+	post: NonNullable<Awaited<ReturnType<typeof ScrimPostRepository.findById>>>,
+) {
 	if (!post.chatCode) return;
 	ChatSystemMessage.send({
 		room: post.chatCode,
 		revalidateOnly: true,
-		authorUserId: user.id,
 	});
 }
 
diff --git a/app/features/sendouq-match/actions/q.match.$id.server.ts b/app/features/sendouq-match/actions/q.match.$id.server.ts
index 7eaf01472..9cb254123 100644
--- a/app/features/sendouq-match/actions/q.match.$id.server.ts
+++ b/app/features/sendouq-match/actions/q.match.$id.server.ts
@@ -103,7 +103,6 @@ export const action = async ({ request, params }: ActionFunctionArgs) => {
 						ChatSystemMessage.send({
 							room: match.chatCode,
 							revalidateOnly: true,
-							authorUserId: user.id,
 						});
 					}
 				}
@@ -156,7 +155,6 @@ export const action = async ({ request, params }: ActionFunctionArgs) => {
 					ChatSystemMessage.send({
 						room: match.chatCode,
 						revalidateOnly: true,
-						authorUserId: user.id,
 					});
 				}
 
@@ -164,7 +162,6 @@ export const action = async ({ request, params }: ActionFunctionArgs) => {
 				ChatSystemMessage.send({
 					room: SENDOUQ_LOOKING_ROOM,
 					revalidateOnly: true,
-					authorUserId: user.id,
 				});
 
 				break;
@@ -237,7 +234,6 @@ export const action = async ({ request, params }: ActionFunctionArgs) => {
 					ChatSystemMessage.send({
 						room: SENDOUQ_LOOKING_ROOM,
 						revalidateOnly: true,
-						authorUserId: user.id,
 					});
 				}
 
@@ -245,7 +241,6 @@ export const action = async ({ request, params }: ActionFunctionArgs) => {
 					ChatSystemMessage.send({
 						room: match.chatCode,
 						revalidateOnly: true,
-						authorUserId: user.id,
 					});
 				}
 
@@ -297,7 +292,6 @@ export const action = async ({ request, params }: ActionFunctionArgs) => {
 					ChatSystemMessage.send({
 						room: match.chatCode,
 						revalidateOnly: true,
-						authorUserId: user.id,
 					});
 				}
 
@@ -322,7 +316,6 @@ export const action = async ({ request, params }: ActionFunctionArgs) => {
 					ChatSystemMessage.send({
 						room: match.chatCode,
 						revalidateOnly: true,
-						authorUserId: user.id,
 					});
 				}
 
@@ -402,7 +395,6 @@ export const action = async ({ request, params }: ActionFunctionArgs) => {
 					ChatSystemMessage.send({
 						room: match.chatCode,
 						revalidateOnly: true,
-						authorUserId: user.id,
 					});
 				}
 
diff --git a/app/features/sendouq/actions/q.looking.server.ts b/app/features/sendouq/actions/q.looking.server.ts
index 996b9d693..228f99525 100644
--- a/app/features/sendouq/actions/q.looking.server.ts
+++ b/app/features/sendouq/actions/q.looking.server.ts
@@ -37,14 +37,12 @@ export const action: ActionFunction = async ({ request }) => {
 		ChatSystemMessage.send({
 			room: SENDOUQ_LOOKING_ROOM,
 			revalidateOnly: true,
-			authorUserId: user.id,
 		});
 
 	const revalidateGroupTopic = (groupId: number) =>
 		ChatSystemMessage.send({
 			room: sqGroupWebsocketRoom(groupId),
 			revalidateOnly: true,
-			authorUserId: user.id,
 		});
 
 	const notifyLikeReceived = (groupId: number) =>
@@ -52,7 +50,6 @@ export const action: ActionFunction = async ({ request }) => {
 			room: sqGroupWebsocketRoom(groupId),
 			type: "LIKE_RECEIVED",
 			revalidateOnly: true,
-			authorUserId: user.id,
 		});
 
 	try {
@@ -215,13 +212,11 @@ export const action: ActionFunction = async ({ request }) => {
 						room: sqGroupWebsocketRoom(ownGroup.id),
 						type: "MATCH_STARTED",
 						revalidateOnly: true,
-						authorUserId: user.id,
 					},
 					{
 						room: sqGroupWebsocketRoom(theirGroup.id),
 						type: "MATCH_STARTED",
 						revalidateOnly: true,
-						authorUserId: user.id,
 					},
 				]);
 
diff --git a/app/features/sendouq/actions/q.preparing.server.ts b/app/features/sendouq/actions/q.preparing.server.ts
index f2818d9ba..188450d50 100644
--- a/app/features/sendouq/actions/q.preparing.server.ts
+++ b/app/features/sendouq/actions/q.preparing.server.ts
@@ -44,7 +44,6 @@ export const action = async ({ request }: ActionFunctionArgs) => {
 				ChatSystemMessage.send({
 					room: SENDOUQ_LOOKING_ROOM,
 					revalidateOnly: true,
-					authorUserId: user.id,
 				});
 
 				return redirect(SENDOUQ_LOOKING_PAGE);
@@ -78,7 +77,6 @@ export const action = async ({ request }: ActionFunctionArgs) => {
 					ChatSystemMessage.send({
 						room: chatCodeToRevalidate,
 						revalidateOnly: true,
-						authorUserId: user.id,
 					});
 				}
 
@@ -95,7 +93,6 @@ export const action = async ({ request }: ActionFunctionArgs) => {
 				ChatSystemMessage.send({
 					room: sqGroupWebsocketRoom(ownGroup.id),
 					revalidateOnly: true,
-					authorUserId: user.id,
 				});
 
 				notify({
diff --git a/app/features/sendouq/actions/q.server.ts b/app/features/sendouq/actions/q.server.ts
index aa39de5a2..3c884d1b6 100644
--- a/app/features/sendouq/actions/q.server.ts
+++ b/app/features/sendouq/actions/q.server.ts
@@ -54,7 +54,6 @@ export const action: ActionFunction = async ({ request, url }) => {
 					ChatSystemMessage.send({
 						room: chatCodeToRevalidate,
 						revalidateOnly: true,
-						authorUserId: user.id,
 					});
 				}
 
@@ -66,7 +65,6 @@ export const action: ActionFunction = async ({ request, url }) => {
 					ChatSystemMessage.send({
 						room: SENDOUQ_LOOKING_ROOM,
 						revalidateOnly: true,
-						authorUserId: user.id,
 					});
 				}
 
@@ -100,7 +98,6 @@ export const action: ActionFunction = async ({ request, url }) => {
 					ChatSystemMessage.send({
 						room: chatCodeToRevalidate,
 						revalidateOnly: true,
-						authorUserId: user.id,
 					});
 				}
 
@@ -120,7 +117,6 @@ export const action: ActionFunction = async ({ request, url }) => {
 					ChatSystemMessage.send({
 						room: sqGroupWebsocketRoom(groupInvitedTo.id),
 						revalidateOnly: true,
-						authorUserId: user.id,
 					});
 				} else {
 					// Joining an active group changes its size/suitability for the whole
@@ -129,7 +125,6 @@ export const action: ActionFunction = async ({ request, url }) => {
 					ChatSystemMessage.send({
 						room: SENDOUQ_LOOKING_ROOM,
 						revalidateOnly: true,
-						authorUserId: user.id,
 					});
 				}
 
diff --git a/app/features/tournament-admin/actions/to.$id.admin.index.server.ts b/app/features/tournament-admin/actions/to.$id.admin.index.server.ts
index 4136fac76..793ad0066 100644
--- a/app/features/tournament-admin/actions/to.$id.admin.index.server.ts
+++ b/app/features/tournament-admin/actions/to.$id.admin.index.server.ts
@@ -123,7 +123,6 @@ export const action: ActionFunction = async ({ request, params }) => {
 			sendDroppedMatchChatMessages({
 				tournamentId: tournament.ctx.id,
 				endedMatchIds,
-				authorUserId: user.id,
 			});
 
 			break;
@@ -196,11 +195,9 @@ async function dropTeamOut({
 function sendDroppedMatchChatMessages({
 	tournamentId,
 	endedMatchIds,
-	authorUserId,
 }: {
 	tournamentId: number;
 	endedMatchIds: number[];
-	authorUserId: number;
 }) {
 	if (endedMatchIds.length === 0) return;
 
@@ -209,13 +206,11 @@ function sendDroppedMatchChatMessages({
 			room: tournamentMatchWebsocketRoom(matchId),
 			type: "TOURNAMENT_MATCH_UPDATED" as const,
 			revalidateOnly: true as const,
-			authorUserId,
 		})),
 		{
 			room: tournamentWebsocketRoom(tournamentId),
 			type: "TOURNAMENT_UPDATED" as const,
 			revalidateOnly: true as const,
-			authorUserId,
 		},
 	]);
 }
diff --git a/app/features/tournament-bracket/actions/to.$id.brackets.server.ts b/app/features/tournament-bracket/actions/to.$id.brackets.server.ts
index 63303928f..fe995a270 100644
--- a/app/features/tournament-bracket/actions/to.$id.brackets.server.ts
+++ b/app/features/tournament-bracket/actions/to.$id.brackets.server.ts
@@ -348,7 +348,6 @@ export const action: ActionFunction = async ({ params, request }) => {
 				room: tournamentWebsocketRoom(tournament.ctx.id),
 				type: "TOURNAMENT_UPDATED",
 				revalidateOnly: true,
-				authorUserId: user.id,
 			},
 		]);
 	}
diff --git a/app/features/tournament-match/actions/to.$id.matches.$mid.server.ts b/app/features/tournament-match/actions/to.$id.matches.$mid.server.ts
index bfaacaf55..a0654faa2 100644
--- a/app/features/tournament-match/actions/to.$id.matches.$mid.server.ts
+++ b/app/features/tournament-match/actions/to.$id.matches.$mid.server.ts
@@ -882,13 +882,11 @@ export const action: ActionFunction = async ({ params, request }) => {
 				room: tournamentMatchWebsocketRoom(matchId),
 				type: "TOURNAMENT_MATCH_UPDATED",
 				revalidateOnly: true,
-				authorUserId: user.id,
 			},
 			...otherMatchIdsToRevalidate.map((id) => ({
 				room: tournamentMatchWebsocketRoom(id),
 				type: "TOURNAMENT_MATCH_UPDATED" as const,
 				revalidateOnly: true as const,
-				authorUserId: user.id,
 			})),
 		]);
 	}
@@ -898,7 +896,6 @@ export const action: ActionFunction = async ({ params, request }) => {
 				room: tournamentWebsocketRoom(tournament.ctx.id),
 				type: "TOURNAMENT_UPDATED",
 				revalidateOnly: true,
-				authorUserId: user.id,
 			},
 		]);
 	}